Power distribution systems can be susceptible to fault conditions. The faults need to be corrected as soon as possible to reduce power outage time and avoid equipment damage. The correction of fault conditions requires an accurate and fast estimation of the locations of the faults.
Several methods have been used for locating multi-phase faults in distribution systems. For example, U.S. Pat. No. 5,682,100 describes traveling wave methods for estimating the fault location. Receiver stations are installed along the power distribution system at locations for sensing and recording time-intervals between each transient fault pulse. The fault location is determined based on these timing intervals, known time delays and the known propagation velocity of the electric power cables in the power distribution system.
The method described in U.S. Pat. No. 8,346,207 uses a similar approach. Multiple radio transceivers are installed at several locations along the distribution feeder and fault location is determined by a central computer comparing the time of arrival of the signals. However both methods require installation of additional fault measurement devices in the power distribution system, which increase cost.
Another method described in U.S. Pat. No. 5,773,980 describes an impedance-based fault location method for multi-phase faults in power distribution networks. That method calculates a fault impedance by correcting errors due to the interaction of fault resistance and load current. However, the method uses an approximate line model for distribution lines.
The method described in U.S. Pat. No. 6,483,435 calculates fault loop impedance to determine the fault location in an event of multi-phase faults. The method uses sequence components of line for fault location thus approximating the distribution line model and allowing approximation errors in the fault location. Also, the method assumes that the fault is resistive and does not include effects of the fault impedance.
Accordingly, there is a need for locating multi-phase faults in the power distribution systems.